Longitudinal associations between weight status and academic achievement in primary school children

Background: Evidence for longitudinal associations between childhood weight status and academic achievement remains unclear due to considerable heterogeneity in study design, measures of academic achievement and appropriate categorization of weight status. Objective: To examine longitudinal associations between childhood weight status (underweight, healthy weight, overweight/obese) and academic achievement in the transition from preschool to primary (elementary) school among Australian school children. Methods: Data were from the Healthy Active Preschool and Primary Years study. Height and weight, for calculating BMI were measured at baseline (preschool age 3–5 years; 2008/9) and follow-up (primary school age 6–8 years; 2011/12). Academic achievement was measured at age 9 years. Results: No associations between BMI z-score or weight category in the preschool years and later NAPLAN scores were found for boys. For girls, having a higher BMI z-score (B = −13.68, 95%CI: −26.61, −0.76) and being affected by overweight (B = −33.57, 95%CI: −61.50, −5.24) in preschool was associated with lower language scores. Remaining affected by overweight from preschool to primary school was associated with lower numeracy (B = −25.03, 95%CI: −49.74, −0.33), spelling (B = −33.5, 95%CI: −63.43, −3.58), language (B = −37.89, 95%CI: −72.75, −3.03) and total achievement scores (B = −24.24, 95%CI: −44.85, −3.63) among girls. For boys, becoming affected by overweight was associated with lower spelling (B = −38.76, 95%CI: −73.59, −3.93) and total achievement scores (B = −27.70, 95%CI: −54.81, −0.58). Conclusions: Associations between being affected by overweight/obesity and poorer academic achievement were more pronounced in girls than boys, indicating potentially inequitable impacts of excess weight and highlighting the greater need for intervention among girls. However, stronger study designs are needed to confirm our findings.